Method for making acid-proof alloys



1 No Drawing.

Patented Feb. 13, 1923.

UNITED STATES PATENT oFFicE.

RICHARD WALTER, 0F DUSSELDORF, GERMANY.

METHOD'FOR MAKING ACID-PROOF ALLOYS.

To all whom it may Be 'it known that German citizen, Germany, have invented certai concern: I, RICHARD WALTER, a-

and resident of Dusseldorf.

n new and useful-Improvements in Methods for Making Acid-Proof Alloysof which the followhod for obsilicon and particularly of in the art the known ironsilicon alloys in their crystallized state are able to dissolve far less carbon than when in liquid state. which'phenomenon is Still more pronounced with increasing silicon content. In consequence alloys of this character, on solidifying, separate out or (liSlIlcorporate again that amount which the liquid of carbon charge had incorporated beyond the eutectic. which segregation product is un'favorably known as foam and which seriously afiects mogeneity of the castings.-

For this reason, and

refining the lioalso for the purpose of reducing the undesirable hardness of the product, prior inventors kept content of these alloys as low only to find that the difficulties cally the carbon as possible. in economimanufacturing such alloys on a large scale increase with the decreasing carbon content, and that it is practically impossible to produce substantially carbon-free alloys of this character.

By extended experiments I have now found that, contrary to prior knowledge. the hardness of the alloy decreases considerably as the carbon content rises, so that, for instance, with a silicon content of between 13 and 25%, and wth a carbon content of not less than 0,65%,

a decided softening occurs.

and that if the carbon percentagels'increased to 0,8% up to 1% a pro duct results Application filed July 16, 1920. Serial No. 396,863.

which can readily be worked by chip-producing tools.

I have further found that these results are attained only it the crystallization is carried through in such manner that the formation of silicon cementite is prevented as much as possible and most of the carbon is changed into its graphite modification. This is best attained by pouring the molten bath into the mold at a temperature just slightly above the fusing point of the alloy. whereas. if the bath is poured at a distinctly higher tem perature, the formation of the hardening silicon cementite cannot be prevented.

The resulting alloy product is of very finegrained homogeneous texture. and is relatively soft and easily workable.

lVhat I claim is 1. The hereinbefore described method of making an acid-proof alloy containing heavy metal. a relatively high silicon content. and over 0,65% of carbon. which consists in melting down said ingredients and pouring the molten bath at a temperature only slightly above the fusing point of the alloy.

2. The hereinbetore described method of making an acid-proof alloy. composed of iron, a relatively high silicon content. and over 0,65% of carbon. which consists in melting down said components and pouring the bath at a temperature only slightly above the fusing point of the alloy.

3. The hereinbefore described making in melting together heavy metal. silicon and carbon. the silicon content being within the limits of 13% and 25%, and the carbon content in excess of 0.65% of the total, and casting the molten bath at a temperature slightly above the fusing point of the alloy. i

In testimony whereof I aflix my signature.

method of RICHARD VALTER. 

